After years of severe stomach pains and other painful symptoms, Jackie discovers she's been suffering from Schistosomiasis, or snail fever.

Only 20 percent of infected individuals will show symptoms of Zika, making it often misdiagnosed. To make matters worse, it can result in devastating birth defects if a woman catches before or during pregnancy.

Charlye Hebert has been experiencing nausea, vomiting and diarrhea for months. Despite an initial diagnosis and treatment for stomach ulcers, her symptoms have yet to subside.

Doctors and family are stunned when they discover the cause of Kennedy's poor health is due to an extreme allergy to nickel, which can be traced to the metal braces on her teeth.

Xander's condition takes a devastating turn when his skin starts peeling off his body.

Now that doctors know what's wrong with Xander, they put him on life support to give him the best chance of recovery.

After spending two months in a coma as a result of a Group A Streptococcus infection, Katy wakes up to the devastating news that all four limbs had to be amputated in order to keep her alive.

After complaining about pain on his head, 8-year-old Andrew is rushed to the ER, where doctors remove a botfly larva from his scalp.

When doctors cannot find anything in his mouth, biology professor John Allen takes matters into his own hands and extracts a rare parasite called Gongylonema pulchrum.

After suffering from an array of symptoms for months, Al Ceccarelli is diagnosed with Strongyloides, a disease caused by parasitic worms found in tropical climates.

As soon as doctors make an incision near Paul’s eye, out pops a larva.

An ovarian teratoma removed from Kira’s body featured hair, teeth, tissue and other cells, resulting in her erratic behavior and sickness.

Sam's worsening flu-like symptoms takes him to the emergency room, where his urine indicates something dangerously wrong with his renal system.

With Brianna's head abrasion getting worse, her parents rush her to the ER where a dermatologist hears something terrifying coming from her scalp.

When a high school football star begins to experience odd symptoms, his parents take him to the hospital.

Stephanie noticed her 4-year-old son, Alex, came home with less energy than usual. But what seemed like the result of a long day at school quickly turned into a race to the emergency room.

When Rich, a journalist just back from West Africa, is feeling so ill he needs to race to the hospital, doctors soon learn it's a parasite called 'Entamoeba histolytiche,' the world's deadliest parasite after Malaria.

When an EMS' own son starts having seizures, a nightmare begins for their entire family. The eventual diagnosis is heartbreaking and doctors are not hopeful.

SNEAK PEEK: When one woman is convinced she has a worm in her eyeball - yet her doctor is not - she decides to take matters into her own hands. Literally. With a pair of tweezers. *shudder*

Well, hopefully you won't experience the kind of horrific discovery one woman made when doctors found a parasite living in her eyeball.

When a doctor discovers a worm in a woman's eyeball, they immediately perform surgery to remove it. Everyone's SHOCKED when they extract a 7- to 8-inch-long worm.

Medical sponges left in your body after surgery can be deadly. Each year as many as 6,000 patients have medical equipment left in their body after surgery. Up to 35% of those with sponges left in their body will die.

When one man hits his head and starts feeling nauseated, he heads to the clinic where doctors make a HORRIFYING discovery: HE HAS A METAL NAIL IN HIS BRAIN. Can he survive and, make a full recovery??

When one young, healthy athlete finds himself weak and in the hospital from the Aspergillus fungus, his immune system goes into overdrive to fight off the infection.

When a woman discovers a bot fly has burrowed into her leg, a doctor takes action to remove the monster immediately - instead of option B, waiting 6 weeks for the little beast to exit on its own.

After one very ill woman experiences her breast secreting yellow pus and begins to turn black, she races to the hospital. Doctors diagnose her with gangrene caused by a spider bite.

When doctors discover a young woman's respiratory system is being attacked by the fungus Cryptococcus gattii, they race to save her life before her lungs fail.

SNEAK PEEK: An entire family is placed in isolation after exposure to their daughter's unidentified illness. As her lungs begin to fail, doctors frantically try to diagnose her before it's too late.

SNEAK PEEK: When one man gets a cut in his mouth and starts spitting up brown fluids, has difficulty breathing and begins smelling like rotting flesh, his parents take him to the hospital where they discover a frightening infection.

When a doctor identifies two large foreign masses in one woman's MRI scan, he comes to the conclusion her brain has been infested with pork tapeworm - which could be fatal.

SNEAK PEEK: A young college student is experiencing migraines, nausea, strange tastes and vision loss. Her family takes her to the doctor … and are horrified when they see a scan of her brain.

Watch as John carves a lifelike pig out of a big block of wood.